A typical web service today is built of many layers of programs and/or computing devices. For instance, an outermost layer is provided that is usually responsible for the socket layer and other communications. One or more intermediate layers exist behind the outermost layer and often control flow or function. In the bottom most layer, most of the business logic is performed. Also, many of the computing devices are placed behind one or more content flow directors, such as a Layer Four (L4) switch, to allow for scalability and fail over. While the layered approach has many advantages, it also creates or avoids fully assessing other problems.
For example, most L4 switches are able to detect whether a port failure has occurred in the computing devices of the outermost layer, to which they are directly connected, and will redirect network traffic to other servers, for example, upon port failure. However, if a problem arises in a layer deeper than the outermost layer, for example, away from the L4 switch, the communications port of the outermost layer will remain fully operational despite the problem. As a result, the L4 will not fail over to other computing devices because its relationship to the outermost communication port has not failed and appears normal.
Accordingly, there is need in the art to assess the health of services that functions deeper than just a check of interfaced ports. While some higher end L4 switches have the capability of testing a full URL path, most cannot. Even those L4 switches that can test full URLs, most only test for very simple HTTP status codes. Accordingly, there is a further need in the art to perform checks more robustly, such as by way of policy-based decisions. Naturally, any improvements should further contemplate good engineering practices, such as relative inexpensiveness, stability, ease of implementation, low complexity, etc. In this regard, implementation of invention without reconfiguring or altering typical configurations of the L4 switches or other content flow directors remains another need in the art.